This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The overall goal of this study is to identify a novel systemic lupus erythematosus (SLE) susceptibility gene among multiplex pedigrees stratified by secondary Sj[unreadable]gren's syndrome. Our effort to find new genes to explain the complex genetic basis of SLE has produced a number of linkage signals. In this project, along with the complimentary effort made by our associated repository of lupus samples, the largest of such repositories in the Unites States, we have adopted a unique pedigree stratification strategy that may help to reduce the enormous genetic heterogeneity of lupus. We have selected the families who have at least one SLE affected individual with a secondary Sj[unreadable]gren's syndrome. This stratification strategy tested the hypothesis that SLE patients with Sj[unreadable]gren's syndrome would identify a more genetically homogeneous group of pedigrees, in which previously undetected linkage effects could be established.